A274093 a(0)=0; thereafter (-1)^n*n appears n times.
0, -1, 2, 2, -3, -3, -3, 4, 4, 4, 4, -5, -5, -5, -5, -5, 6, 6, 6, 6, 6, 6, -7, -7, -7, -7, -7, -7, -7, 8, 8, 8, 8, 8, 8, 8, 8, -9, -9, -9, -9, -9, -9, -9, -9, -9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, -11, -11, -11, -11, -11, -11, -11, -11, -11, -11, -11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12
Offset: 0
Keywords
Links
- Chai Wah Wu, Table of n, a(n) for n = 0..10011
Programs
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Maple
s1:=[0]; for n from 1 to 15 do for i from 1 to n do s1:=[op(s1),(-1)^n*n]; od: od: s1; -
Mathematica
Join[{0}, Flatten[Table[(-1)^n*n, {n, 15}, {n}]]] (* Paolo Xausa, Sep 30 2024 *) Join[{0},Table[PadRight[{},n,If[EvenQ[n],n,-n]],{n,15}]]//Flatten (* Harvey P. Dale, Dec 06 2024 *) -
Python
A274093_list = [0]+ [i for n in range(1,142) for i in [-n if n % 2 else n]*n] # Chai Wah Wu, Jun 11 2016
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Python
from math import isqrt def A274093(n): return -m if (m:=isqrt(n<<3)+1>>1)&1 else m # Chai Wah Wu, Nov 05 2024